I propose two features for vertical rest positioning:
Please, make available a keyboard shortcut to move a rest up or down, in the same way we move notes (ALT+arrow UP/DOWN). This would be a very good improvement! (if it is already possible, please, give me a hint!).
When selecting “Rest pos.” property, it would be very useful to keep the rest position. Most of the time I only want to move the rest just one or two spaces up or down and if rest goes to the “0” position I have to move it a lot of spaces (specially when more than one voice is involved).